MSefi.com read only forum (Jan.15,2018)

3 months ok i had the car tuned ok... it would idle and rev just fine ... do to lack of money i had to let it sit for awhile now it runs hot, backfires when i rev it above 1500 and the exhaust pipes get very hot!! enough to make the undercarrage start smoking only thing that changed is a few of the injectors where leaking fuel on the pressure side but i fixed that by replacing a few o rings....

Sounds like it may be way too lean! What does your afr gauge tell you?

You certainly don't want to run it long like that!

Ken

bmcewen,

Yup, I agree with Ken, it's likely lean. This may be because the fuel filter is plugged, the fuel pump is clogged, or some/all of the injectors are clogged - any of these can happen from sitting too long, especially if the entire fuel system wasn't originally designed for EFI. It's not impossible that the fuel pressure regulator isn't maintaining the desired pressure either, and again this can be due to junk getting in it.

Lance.

Well after i posted i started trying to fiddle with it a little and found i have some leaking injectors...the entire fuel system is new with the exception of the tank itself so i wouldn't be supprised if it were just debris from initial start up. Is there any good way to tell which injectors may be clogged or leaking? the one i know is leaking because of the presence of fuel when i pull the spark plug so i thought it was backfireing due to unburnt fuel igniting in the exhaust which doesn't seem possible under a lean condition...anyhow i bought another set of injectors so when they get here today i will install them and look for possible lean conditions i don't really recall the afr going above 15.5 ish in park revving to around 2k

i wouldn't be supprised if it were just debris from initial start up

You also need to ensure that the lines are devoid of debris and then install a very good filter to keep this from happening again!

Frankly though, what you described, still sounds like a lean condition, which wouldn't be caused by leaking injectors IMO.

Ken

Well I think that its a little of both, some injectors are clogged while some are leaking so some cylinders are rich while others are lean. I used compressed air to blow out the new fuel lines when I installed them and have a Russel 10 micron inline fuel filter as well as the intank filter on the walbro, I took apart the inline filter this morning and there wasn't any debris in it... 2 plugs are black and sooty three plugs where almost white the others looked normal

Sorry the inline filter is a 40 micron

Last thoughts for the day...after spending a few hours tuning I'm wondering if one leaking injector could cause the o2 to read rich therefore causing the rest of the cylinders to go lean in order to compensate...autotune and ve analyzer kept trying to lean everything out so I scrapped the msq reloaded one from 3 months ago and everything kinda smoothed out